High efficiency ignition system



Oct. 31, 1961 w. R; KAPPELE 3,007,082

HIGH EFFICIENCY IGNITION SYSTEM Filed June 11, 1959 TO DISTR BUT I AND SPAR K P3555 I V0 I-TAG E VOL-TAG E VOLTAGE 3 la a [I 6' TIME 4 WILLIAM R. KAPPELE INVENTOR.

ATTOE N ENS nited rates dice 3,007,082 HIGH EFFICIENCY IGNITION SYSTEM William R. Kappele, 5615 Ave. A, Torrance, Calif. Filed June 11, 1959, Ser. No. 819,598 2 Claims. (Cl. 315-414) This invention relates generally to internal combustion engine ignition systems and more particularly concerns an improved ignition system incorporating means acting to increase energy storage in the ignition system coil and thereby to transfer greater energy to the spark plugs, through the suppression of arcing at the ignition system breaker points or contacts.

In conventional internal combustion engine ignition systems the breaker points are subject to excessive burning and wear, necessitating their replacement at frequent intervals, brought about as a result of excessive arcing .across the points when they are opened. In an effort to cut down such unwanted arcing, it is customary to open the points rapidly and in excess of the gap width at which no arcing can occur. This practice reduces the interval of time during which the points dwell together, or are closed during the time intervals between opening of the points. Consequently, the forward flow of current through the coil to build up the electromagnetic field and store energy therein is limited by the dwell time of the points, and it is readily seen that increasing the extent of opening or the gap of the points to reduce arcing has the undesirable effect of decreasing energy storage in the coil. As a practical matter, the longest dwell time of points in conventional automotive engines is around 50%; that is, the points are closed no longer than 50% of the total time.

The present invention has for its major object to substantially increase the dwell time of point closure and thereby to increase the energy delivered to the distributor and spark plugs of the engine, by controlling or reducing arcing at the breaker points so that the latter need not be opened to the extent now required in practice. Also, the invention contemplates improved damping of the spark at the spark plugs at low engine speeds, so as to maintain more constant sparking efliciency throughout the entire speed range of the engine. Such spark damping extends spark'plug life by preventing useless burning of plug points.

In furtherance of these objects, the invention contemplates the provision of unidirectional conductive means in an internal combustion engine ignition system that includes a source of low voltage direct current, a circuit interrupter and primary and secondary coils. The unidirectional conductive means, which preferably comprises a silicon diode, is electrically connected in series relation with the primary coil and in parallel relation with the interrupter or breaker points, or it may be connected in parallel relation with the primary coil and in series relation with the interrupter. Furthermore, the unidirectional means has its direction of electrical conductivity in opposition to the direction of current flow acting to increase the flux density in the primary coil when the points are closed. As a result, when these points or contacts are opened, current tends to flow through the unidirectional conductive means instead of arcing directly across the contacts. At the same time, the dwell time of the interrupter or breaker points is made substantially greater than the time intervals during which the contacts are opened, all without resulting in undesirable arcing at the breaker points, so that energy storage in the primary coil and energy delivery to the spark plugs is substantially increased.

The invention also contemplates the provision of a resistor connected in series with the unidirectional conductive means for limiting the discharge time of the coil when the breaker points are opened, and thereby damping sparking at the plugs to extend plug life at low engine speeds. Such damping of the spark actually results from a damping of the oscillations of an oscillatory circuit which includes a primary coil and a condenser connected in series with the coil and across the breaker points.

These and other objects of the invention, a well as the details of an illustrative embodiment, will be more fully understood from the following detailed description of the drawings, in which:

FIG. 1 is a circuit diagram showing the improved internal combustion engine ignition system;

FIGS. 2a and 2b show the time decay of voltage oscillations in the primary coil circuit, respectively without and with the unidirectional conductive means included therein;

FIGS. 3a and 3b show the time decay of voltage oscillations at the spark plugs, respectively without and with the unidirectional conductive means in the primary coil circuit;

FIG. 4 shows interrupter mechanism having increased contact dwell time; and

FIG. 5 is a modified circuit diagram of the improved ignition system.

In FIG. 1, the engine battery or direct current source is indicated at It} with the negative terminal of the battery connected to ground and the positive terminal of the battery connected to one terminal of the primary coil 11, having inductance L. The opposite terminal of the coil is electrically connected with one point 12 of the interrupter or circuit breaker 13, and the second breaker point 14 is grounded. A condenser 15 having capacitance C is connected across the breaker points as shown. It will be understood that one of the breaker points is movable to close against and separate from the other breaker, point in response to engine operation, as by actuation of a cam.

Connected in series relation with primary coil 11 and in parallel relation with the interrupter 13 is a unidirectional conductive device 16 having its direction of electrical conductivity in opposition to the direction of current flow fromthe battery 10 acting to increase the flux density in the primary coil 11. Device 16 has its positive terminal connected through a damping resistor 17 with point P of the circuit as shown. Device 16 preferably compnises a silicon diode which has high current capacity and is able to withstand high operating temperatures, say F. On the other hand, other types of unidirectional conductive devices which are usable include selenium rectifiers, copper oxide rectifiers and germanium diodes. Also, the DC. resistance of coil primary and the forward resistance of diode may make use of additional resistance unnecessary.

Inductively coupled with the coil 11 is a secondary coil 18 which is electrically connected to the engine distributor and spark plugs. In operation, when the breaker points 12 and 14- are closed, an electrical circuit is completed from the battery through the coil primary 11 and through the breaker points 12 and 14 to ground. No appreciable current flows at this time through the device 16, since its impedance is presented to the positive terminal of the battery source. On the other hand, when the points 12 and 14 are separated, the energy stored in the coil 11 commences to dissipate and the series circuit including the coil and the condenser 15 commences to resonate. At the same time, a unidirectional circuit is completed through coil 11, resistor 17 and device 16, whereby current may flow in opposition to the direction of initial current flow acting to increase the flow density in the primary coil.

In practical effect, the resonant voltage oscillations appearing at points P are as shown in FIG. 2b indicating that the negative surges of voltage are clipped by the action of the unidirectional conductive device 16. As the breaker points 12 and 14 open, the are which would be formed by the initial surge of negative voltage is extinguished due to clipping of the negative voltage surge, say at approximately 12 volts with a 750 mil diode 16 and a 15 ohm resistor 17, the battery having 12 volts delivery. Furthermore, resistor 17 acts to damp the voltage oscillations which would, in the absence of the diode 16 and resistor 17, appear as in FIG. 2a.

Referring to FIGS. 3a and 3b, it is apparent that the voltage oscillations at the spark plugs are damped by the action of the diode 16 and resistor 17 in relation to the voltage oscillations which would otherwise exist in the absence of those circuit elements. This damping effect is of significance at lower engine speeds and substantially decreases spark plug burning and erosion, thereby improving the efiiciency of engine operation. Moreover, more electrical energy is fed to the spark plugs from the coil at high speeds, since the breaker points are closed for longer intervals of time.

Referring to FIG. 4, the breaker point or contact 14 is shown carried by a lever 24 pivoted at 21 in the conventional manner. The contact 14 is urged toward the fixed contact 12 by means of a flat coil spring 22, one end of which is mounted on the post 23, the opposite end of which is connected to the lever 24 for urging the latter in a rotary direction toward a rotatable cam 25. The cam is keyed to a rotor 26 driven by the engine, the cam rotor shaft normally rotating once for each two revolutions of the engine crank shaft. As shown, the cam has six lobes 27 corresponding to its use on a six cylinder engine; however, it will be understood that the number of lobes is merely illustrative. As the cam rotates, an insulated bumper block 28 mounted on the lever 20 rides against the cam fiat sides 29 and over the lobes 27. Thus, cam rotary engagement with the bumper 28 causes the lever 24 to rotate and counter-rotate, moving the contact 14 toward and away from the fixed contact 12.

As previously mentioned, the fixed contact 12 mounted on adjustable screw 30 is positioned to stop counterrotation of the lever in a location such that the lever undergoes active rotation and counter-rotation during less than 180 of earn rotation. In other words, the points 1.2 and 13 dwell together or are closed for substantially longer intervals of time than they are open and preferably they dwell together between 75 and 80 percent of the time. Such extent of dwell results in increased buildup of the flux density associated with the coils 1.1 and 1t and concomitant increased energy delivery to the spark plugs when the breaker points are separated. Correspondingly, it has been found that the breaker points need be separated or opened by only about .008 inch in order to extinguish arcing, the maximum opening of the points in practice amounting to about .020 inch. Another advantage resides in the elimination of bouncing of the breaker arm or lever 24 at high engine speeds, such action resulting from mechanical resonance conditions occurring at higher engine speeds where the breaker point maximum gap opening is considerably in excess of .020 inch as in conventional ignition systems. Since the amount of gap or breaker point opening is kept very small the bouncing problem creating faulty ignition may now be eliminated.

Referring now to FIG. 5 the elements of the circuit shown are the same as shown in FIG. 1 with the exception that the undirectional conductive means 15 and resistor 17 are now connected in parallel relation with the coil 11 and in series relation with the interrupter 13. Here again, the positive terminal of the device 16 is directly connected with the positive terminal of the battery 10 so that no appreciable current flows from the battery through the device 16; that is to say, device 16 has its direction of conductivity in opposition to the direction of current flow acting to increase the flux density in the primary coil 11. While the FIG. 5 arrangement acts to suppress arcing across the points 12 and 1.4, it suffers from the disadvantage that it delays collapse of the field associated with the coil 11 upon separation of the breaker points. Therefore, although the device of FIG. 5 is usable, the device of FIG. 1 is preferred.

1 claim:

1. In combination with an internal combustion engine ignition system including a battery source of low voltage direct current, a circuit interrupter, a primary coil connected in series circuit relation between said interrupter and current source, said coil having an end terminal connected in series with a terminal of the battery, and a secondary coil inductively coupled with said primary coil and from which high voltage current is intermittently supplied to an engine spark plug, said interrupter having contacts alternately closed to pass current fiow from the battery source acting to increase the llux density in said primary coil and opened to interrupt said current flow, unidirectional conductive means including a current rectifier electrically connected in series relation with said battery and electrically connected with said primary coil and interrupter, the connection with one of said primary coil and interrupter elements being in series and with the other in parallel, said means having its direction of electrical conductivity in opposition to the direction of said current flow from the battery so that when said contacts are opened current tends to flow through said means instead of arcing across said contacts, said contacts being closed substantially in excess of half the time during operation of said interrupter, said interrupter including a spring acting to effect closing of said contacts and a rotary cam operable to eirect opening of said contacts, said contacts having a maximum gap opening therebetween which is less than the opening required to extinguish arcing thereacross in the absence of said rectifier.

2. The invention as defined in claim 1 in which said unidirectional conducting means comprises a high temperature silicon diode electrically connected in series relation with said primary coil and in parallel relation with said interrupter contacts, and said contacts are closed at least of the time during operation of the interrupter.

References Cited in the file of this patent UNITED STATES PATENTS 2,382,808 Ochsenbein. Aug. 14, 1945 

